This application is directed to coating systems for applying labels to bottles and aluminum cans. More particularly, this application is directed to heat-activatable labeling systems formed from blends of epoxy and phenoxy resins, polyester resins, or vinyl chloride-vinyl acetate polymers. The labels are fabricated from pigmented resin coatings that provide heat activatable and abrasion resistant features without requiring separate thermoplastic adhesive and protective, abrasion resistant layers or extensive beat curing conditions.
Current labels being used for heat transfer application to glass, plastic, and aluminum containers are manufactured by applying to a release-coated substrate multi-layer components including a heat activatable adhesive layer, colored solid or design areas, and a clear, abrasion resistant protective topcoat to prevent scratching and marring during the filling or subsequent contact of the labelled containers. Use of this system results in substantial raw material, printing and coating costs as well as potential inter layer adhesion problems associated with bonding of the ink layers to the adhesive and topcoat lacquer. Thus, there is a need for a more economical labelling system that can be manufactured more easily while providing required resistance properties without requiring costly post-curing conditions.
It is an object of the invention to provide a labelling system that will not require separate printing and coating stations requiring added raw material adhesive and protective coated areas with associated drying and print registration problems.
It is also an object of the invention to improve the quality of the label by eliminating any potential interlayer adhesion deficiencies during processing and storage of the containers.
It is a further object of the invention to provide a method of producing labels that have improved resistance to solvents and other chemicals and that are non-hazing, clear, and glossy under conditions of pasteurization and immersion in ice water.
Another object of the invention is to provide a better appearance of the label which has no visible edges attributable to the presence of adhesive and topcoat areas.
These and other objects of the invention will become more apparent from the discussion below.
The current invention achieves the desired characteristics of heat activation, adhesion to glass, aluminum, and plastics substrates, abrasion resistance, and chemical resistance by utilizing pigmented solutions of blends of epoxy and phenoxy resins combined with a melamine formaldehyde cross-linking agent and an amine neutralized acid phosphate or an amine neutralized p-toluene sulfonic acid blocked catalyst. The resulting formulations are low enough in viscosity to be applied by flexographic or gravure coaters and presses. The dried films of these products have excellent interlayer adhesion in areas where multiple ink layers overlap.
According to a first embodiment of the invention, the heat-transfer label is particularly well-suited for use on silane-treated glass containers of the type that are subjected to pasteurization conditions, regardless of whether the glass containers have been pre-treated previously with polyethylene, oleic acid, stearate or the like. The heat transfer label comprises (a) a support portion consisting of a sheet of paper or film overcoated with a layer of releasable material such as polyethylene and (b) a transfer portion over said support portion for transfer of the transfer portion from the support portion to an article, upon application of heat to the support portion, and placing the transfer portion in contact with the article.
According to another aspect of the invention, the heat-transfer label is particularly well-suited for use on aluminum cans that have been treated with a highly lubricating acrylic coating or varnish of the type used to prevent scratching and abrasion of such cans (said varnish either being used alone or in combination with a white ink). The heat-transfer label comprises (a) a support portion consisting of a sheet of paper or film overcoated with a layer of releasable material such a polyethylene and (b) a transfer portion over said support portion for transfer of the transfer portion from the support portion to an article, upon application of heat to the support portion, and placing the transfer portion in contact with the article.
It is to be understood that certain terms used herein, such as xe2x80x9conxe2x80x9d or xe2x80x9coverxe2x80x9d, when used to denote the relative positions of two or more layers of the heat transfer label are primarily used to denote such relative positions in the context of the way in which those layers are situated prior to transfer of the transfer portion of the label to an article since, after transfer, the arrangement of layers is inverted as those layers that were furthest removed from the associated support sheet are now closest to the labelled article.